One way to construct materials atom by atom is
to conscript machinery nature has already devised.
Scientists have methods of making round particles that are as small as
one nanometer, which is the span of 10 hydrogen atoms. But making more
complicated shapes is more difficult.
Researchers from the University of Bristol in England, Vanderbilt
University, and the University of Maryland have found that they can fill
or coat a long, cylindrical tobacco virus with metal particles.
The method could eventually be used to manufacture structures like
metal nanowires that could be used in electronics or optics devices,
according to the researchers.
The researchers mixed the 4- by 60-nanometer virus with gold, silver
and platinum salts. In an acidic pH solution, negatively-charged metal
salts reacted with viral amino acids to cause nanoparticles to align on
the outer surface of the virus. In a neutral pH solution,
positively-charged salts passed through the viruses' protein coats,
causing metal nanoparticles to align inside the viruses.
The researchers showed that mutating the amino acids affects where the
metal particles deposit.
The method to be used practically in 10 to 20 years, according to the
researchers. The work appeared in the March 12, 2003 issue of Nano
Letters.
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